Product category:
Power Supply ICs and Controllers
News Release from: Micrel | Subject: MIC2287/9
Edited by the Electronicstalk Editorial
Team on 23 January 2004
Boost convertors cut LED drive component
count
Two new small sized DC/DC boost convertors are optimised for driving white LEDs in cellular, PDA, GPS, digital still camera and camcorder applications.
Two new small sized DC/DC boost convertors are optimised for driving white LEDs in cellular, PDA, GPS, digital still camera and camcorder applications The MIC2289 offers the smallest total size PWM DC/DC boost solution available in the market
This article was originally published on Electronicstalk on 5 Dec 2000 at 8.00am (UK)
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The MIC2289 is available in a tiny 2 x 2mm MLF-8L package with a high level of protection and performance features.
The MIC2289 requires only four external components to provide a complete white LED driver solution.
The low component count is achieved by integrating the external Schottky diode normally required with boost regulators, saving precious board area and cost.
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The MIC2287 is similar to the MIC2289, except it operates with an external Schottky diode.
The MIC2287 is best suited for higher power applications that would benefit by sharing the IC power dissipation with an external Schottky diode.
The MIC2287 is available in a 2 x 2mm MLF-8L package, as well as a low profile Thin SOT23-5L package.
Both devices operate with a 2.5 to 10V input voltage range, making them suitable for one- and two-cell Li-ion applications.
Their output voltage achieves up to 34V, allowing the MIC2287/9 to power up to eight white LEDs in series.
The devices have a high 500mA switch current rating, allowing them to provide the higher current necessary in applications such as camera flash LED drivers.
The MIC2287/9 implement high frequency 1.2MHz PWM control, allowing small external components and low noise operation.
The constant frequency PWM control of the MIC2287/9 significantly reduces input ripple and noise compared to variable-frequency PFM boost convertor solutions.
In many cases, this allows designers to reduce their input capacitance from 10 to 1uF.
The low input ripple is especially important in reducing noise injected into the main power line in sensitive RF applications such as cellular phones.
The MIC2287/9 offer a high level of safety with three levels of overvoltage protection (OVP).
The OVP feature protects the IC and external components in case of fault conditions that would cause the boost regulator to generate uncontrolled high voltages.
Many other solutions require external OVP circuitry, or only offer a single high-voltage OVP.
The three MIC2287/9 OVP options of 15, 24 and 34V give customers the flexibility to use lower cost and smaller size low-voltage-rating output capacitors.
"The MIC2287 and MIC2289 literally boost Micrel's strength in the portable market.
These devices save valuable board space without sacrificing either efficiency or noise performance.
The devices achieve over 80% efficiency across the Li-ion battery voltage range, saving valuable battery life.
This compares to many charge-pump solutions that claim high efficiency at a single input voltage but actually have efficiency values as low as 60% across the normal battery voltage range.
Additionally, the MIC2287/9 feature a tight line regulation of less than 1%, meaning the LED current will not change with input voltage, giving a constant brightness across the life of the battery", says Tony Grizelj, Micrel's Marketing Manager for Power Products.
The MIC2287 is available in 2 x 2mm MLF-8L and thin SOT23-5L package options.
The device is priced at $1.06 and $1.13 in 1000-piece quantities, respectively.
The MIC2289 is available in the 2 x 2mm MLF-8L package.
The device is priced at $1.22 in 1000-piece quantities.
Samples are available from stock, and production quantities are stock to 12 weeks ARO.
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